\(a,y'=8x^3-9x^2+10x\\ \Rightarrow y''=24x^2-18x+10\\ b,y'=\dfrac{2}{\left(3-x\right)^2}\\ \Rightarrow y''=\dfrac{4}{\left(3-x\right)^3}\)

\(c,y'=2cos2xcosx-sin2xsinx\\ \Rightarrow y''=-5sin\left(2x\right)cos\left(x\right)-4cos\left(2x\right)sin\left(x\right)\\ d,y'=-2e^{-2x+3}\\ \Rightarrow y''=4e^{-2x+3}\)

a: y=ln(x+1)

=>\(y'=\dfrac{1}{x+1}\)

=>\(y''=\dfrac{1'\left(x+1\right)-1\left(x+1\right)'}{\left(x+1\right)^2}=\dfrac{-1}{\left(x+1\right)^2}\)

b: y=tan 2x

=>\(y'=\dfrac{2}{cos^22x}\)

=>\(y''=\left(\dfrac{2}{cos^22x}\right)'=\dfrac{-2\cdot cos^22x'}{cos^42x}=\dfrac{-2\cdot2\cdot cos2x\left(cos2x\right)'}{cos^42x}\)

\(=\dfrac{4\cdot2\cdot sin2x}{cos^32x}=\dfrac{8\cdot sin2x}{cos^32x}\)

a: \(y=x\cdot e^{2x}\)

=>\(y'=\left(x\cdot e^{2x}\right)'\)

\(=x\cdot\left(e^{2x}\right)'+x'\cdot\left(e^{2x}\right)\)

\(=e^{2x}+2\cdot x\cdot e^{2x}\)

\(y''=\left(e^{2x}+2\cdot x\cdot e^{2x}\right)'\)

\(=\left(e^{2x}\right)'+\left(2\cdot x\cdot e^{2x}\right)'\)

\(=4\cdot e^{2x}+4\cdot x\cdot e^{2x}\)

b: \(y=ln\left(2x+3\right)\)

=>\(y'=\dfrac{\left(2x+3\right)'}{\left(2x+3\right)}=\dfrac{2}{2x+3}\)

=>\(y''=\left(\dfrac{2}{2x+3}\right)'=\dfrac{2\left(2x+3\right)'-2'\left(2x+3\right)}{\left(2x+3\right)^2}\)

\(=\dfrac{4}{\left(2x+3\right)^2}\)

a: \(y'=\left(x^2+2x\right)'\left(x^3-3x\right)+\left(x^2+2x\right)\left(x^3-3x\right)'\)

\(=\left(2x+2\right)\left(x^3-3x\right)+\left(x^2+2x\right)\left(3x^2-3\right)\)

\(=2x^4-6x^2+2x^3-6x+3x^4-3x^2+6x^3-6x\)

\(=5x^4+8x^3-9x^2-12x\)

b: y=1/-2x+5 

=>\(y'=\dfrac{2}{\left(2x+5\right)^2}\)

c: \(y'=\dfrac{\left(4x+5\right)'}{2\sqrt{4x+5}}=\dfrac{4}{2\sqrt{4x+5}}=\dfrac{2}{\sqrt{4x+5}}\)

d: \(y'=\left(sinx\right)'\cdot cosx+\left(sinx\right)\cdot\left(cosx\right)'\)

\(=cos^2x-sin^2x=cos2x\)

e: \(y=x\cdot e^x\)

=>\(y'=e^x+x\cdot e^x\)

f: \(y=ln^2x\)

=>\(y'=\dfrac{\left(-1\right)}{x^2}=-\dfrac{1}{x^2}\)

`a)TXĐ:R\\{1;1/3}`

`y'=[-4(6x-4)]/[(3x^2-4x+1)^5]`

`b)TXĐ:R`

`y'=2x. 3^[x^2-1] ln 3-e^[-x+1]`

`c)TXĐ: (4;+oo)`

`y'=[2x-4]/[x^2-4x]+2/[(2x-1).ln 3]`

`d)TXĐ:(0;+oo)`

`y'=ln x+2/[(x+1)^2].2^[[x-1]/[x+1]].ln 2`

`e)TXĐ:(-oo;-1)uu(1;+oo)`

`y'=-7x^[-8]-[2x]/[x^2-1]`

Lời giải:
a.

$y'=-4(3x^2-4x+1)^{-5}(3x^2-4x+1)'$

$=-4(3x^2-4x+1)^{-5}(6x-4)$

$=-8(3x-2)(3x^2-4x+1)^{-5}$

b.

$y'=(3^{x^2-1})'+(e^{-x+1})'$

$=(x^2-1)'3^{x^2-1}\ln 3 + (-x+1)'e^{-x+1}$

$=2x.3^{x^2-1}.\ln 3 -e^{-x+1}$

c.

$y'=\frac{(x^2-4x)'}{x^2-4x}+\frac{(2x-1)'}{(2x-1)\ln 3}$

$=\frac{2x-4}{x^2-4x}+\frac{2}{(2x-1)\ln 3}$

d.

\(y'=(x\ln x)'+(2^{\frac{x-1}{x+1}})'=x(\ln x)'+x'\ln x+(\frac{x-1}{x+1})'.2^{\frac{x-1}{x+1}}\ln 2\)

\(=x.\frac{1}{x}+\ln x+\frac{2}{(x+1)^2}.2^{\frac{x-1}{x+1}}\ln 2\\ =1+\ln x+\frac{2^{\frac{2x}{x+1}}\ln 2}{(x+1)^2}\)

e.

\(y'=-7x^{-8}-\frac{(x^2-1)'}{x^2-1}=-7x^{-8}-\frac{2x}{x^2-1}\)

g: \(y=ln\left(x^2+x+1\right)\)

=>\(y'=\dfrac{\left(x^2+x+1\right)'}{x^2+x+1}=\dfrac{2x+1}{x^2+x+1}\)

l: \(y=\dfrac{lnx}{x+1}\)

=>\(y'=\dfrac{\left(lnx\right)'\cdot\left(x+1\right)-\left(x+1\right)'\left(lnx\right)}{\left(x+1\right)^2}\)

=>\(y'=\dfrac{\dfrac{1}{x}\left(x+1\right)-lnx}{\left(x+1\right)^2}\)

\(\Leftrightarrow y'=\dfrac{\dfrac{\left(x+1\right)}{x}-lnx}{\left(x+1\right)^2}\)